Cant make Door Open

Hello everyone i have followed many tutorials about a simple door opening script but i cant figure it out.So what ive donw is make an empty game object and parent it to the door.My script is this :

 using UnityEngine;
 using System.Collections;
 
 public class DoorOpen : MonoBehaviour
 {
 
     public bool IsOpen = false;
     public float DoorOpenAngle = 90f;
     public float DoorCloseAngle = 0f;
     public float Smooth = 2f;
 
 
     void Start()
     {
 
     }
     public void ChangeDoorState()
     {
         IsOpen = !IsOpen;
     }
 
     void update()
     {
         if (IsOpen)
         {
             Quaternion TargetRotationOpen = Quaternion.Euler(0, DoorOpenAngle, 0);
             transform.localRotation = Quaternion.Slerp(transform.localRotation, TargetRotationOpen, Smooth * Time.deltaTime);
         }
         else
         {
             Quaternion TargetRotationOpen = Quaternion.Euler(0, DoorCloseAngle, 0);
             transform.localRotation = Quaternion.Slerp(transform.localRotation, TargetRotationOpen, Smooth * Time.deltaTime);
         }
 
     }
 }

In order to test it i simply move mi script to door inspector i hit play then pause and set the bool to true but the door doesnt open...What do i miss??